1. Field of the application
The present invention relates to methods of manufacturing high-grade metallurgical fuel, such as coke and gas containing hydrogen and carbon monoxide, and more particularly, to a dry coke quenching process and apparatus for effecting same.
A further growth in the production of pig iron and steel taking place in the industrially developed and developing countries, as well as the resultant higher consumption of coke, generate a need for new resources of coking coals. Limited reserves of high-grade coking coals and their high cost on the world market stimulate a search for new methods of effective utilization of organic mass of the coking coals for the use in the blast-furnace production.
In modern practice only 70 percent of the coking-coal organic mass is used for the blast-furnace process, while the remaining 30 percent is utilized in the form of solid, liquid and gaseous products for other needs or even in other branches of industry. Moreover, the coke obtained from coke ovens according to the production process now in use contains an appreciable amount of heat which formerly found no application and was released into the atmosphere together with steam formed in the process of dry quenching of said coke.
2. Description of the prior art
At the first stage of improvement of the coke production process a dry coke quenching process was developed wherein a sensible heat of coke was initially utilized for the production of the process steam and then of the energy-producing steam.
For example, there is known a dry coke quenching process ("Technologia koksokhemicheskogo proizvodstva", Coke Chemistry Engineering, published in 1966 by "Metallurgy" Publishing House, written by P. E. Leobovich ed altrum), according to which process the dry quenching of coke is effected by passing a flow of inert gas, such as nitrogen or products of combustion of coke or blast-furnace gases, into a dry quenching chamber.
There is also known an apparatus for carrying the abovementioned process into effect (USSR Inventor's Certificate Nos. 217, 359, ICI C 10b, H cl. 10a, 17/04; 10a 17/07).
Both the apparatus and process for dry quenching of coke suffer from a disadvantage which lies in low efficiency of the coke cooling process which necessitates larger working dimensions of, and, consequently, higher manufacturing cost for, dry coke quenching apparatus.
In addition, by using inert gases in the dry coke quenching process, the effectiveness of utilization of the coking-coal organic mass as well as the quality of coke remain unaltered with regard to its abrasion strength and sulphur-content characteristics.
The dry coke quenching process described in FRG Pat. No. 1,085,495, according to which dry quenching of coke is effected by a mixture of hydrocarbons, steam and oxygen or air, was the first attempt to improve the quality of coke by means of lowering sulphur content therein.
The dry coke quenching process according to the patent referred to above is carried out in a hopper provided with an inclined meshed bottom and adapted to receive therein incadescent coke from a plurality of coke ovens. Introduced from underneath through the meshed bottom is hydrocarbon-containing coke-oven gas and a mixture of steam and oxygen or steam and air. The interaction of hydrocarbons with oxygen and steam results in the formation of hydrogen on the surface of incadescent coke, necessary for its desulphurization, as well as in the evolution of additional amount of heat also required for the coke desulphurization. The content of sulphur in coke is thus lowered.
On escaping from the dry quenching chamber, the hot gas containing hydrogen and sulphur compounds is passed to a waste-heat boiler and then to a sulphur-absorption tower, whereupon, cooled and free from sulphur compounds, it is introduced together with the initial gas-steam mixture into the dry quenching chamber. The disadvantage of this method lies in low efficiency of the coke cooling process, resulting from additional liberation of heat upon interaction of oxygen with hydrocarbons of gaseous mixture and with hydrocarbon of coke. A low content of useful reducing components (Co+H.sub.2) and a high content of inert constituents (N.sub.2, CO.sub.2 and H.sub.2 O), in the obtained gas renders the latter unsuitable for the use in the blast-furnace process.
The quality of coke as to its abrasion strength characteristics and the effectiveness of utilization of the coking-coal organic mass in the blast-furnace process remain unimproved. The apparatus for carrying into effect the above-described process suffers from constructional deficiencies; it is cumbersome and is, therefore, difficult to be appropriately positioned in modern coke shops furnished with large-capacity ovens.
French Pat. No. 1,300,290 teaches a method according to which dry quenching of coke is effected not by inert gases but by a mixture of hydrocarbons, steam and oxygen or air. Coke-oven gas is used as the hydrogen-containing gas in the cooling mixture. This method is considered to be the first attempt aimed at raising effectiveness of utilization of the coking-coal organic mass for employment in the blast-furnace process.
The apparatus for carrying the above-described method into effect is constructionally similar to that described in USSR Inventor's Certificate No. 217,239.
Resulting from the interaction of steam and oxygen with hydrocarbons is gas containing hydrogen and carbon monoxide. The use of gas (reducing gas) containing hydrogen and carbon monoxide in the blast-furnace process makes for lower consumption of coke and a higher production output of a blast furnace. Therefore, the effectiveness of utilization of the coking-coal organic mass in the blast-furnace process is somewhat increased.
The method of the patent referred to above, however, suffers from a disadvantage, it being low efficiency of the coke dry quenching process. The presence of oxygen in the cooling mixture, interacting with the hydrocarbons of gaseous mixture and with the hydrocarbon of coke, leads to additional liberation of heat and to lower rate of coke cooling. As a result, the working dimensions of, and the manufacturing cost for, the dry coke quenching apparatus are increased, whereas specific yield of gas containing hydrogen and carbon monoxide is decreased. Moreover, the quality of coke as to its abrasion strength and sulphur-content characteristics remains unimproved, whereas the coke yield is reduced due to its gasification by 1.6 to 2.0 percent.